Coal stoker



Patented June 11, 1940 UNITED STATES PATENT OFFICE COAL STOKER Ind.

Application August 18, 1938, Serial No. 225,509

7 Claims.

This invention relates to a coal stoker of a structure which may be employed in heating units of the domestic type such as are used in dwellings and the like. The stoker herein described is particularly adapted to feed and burn the lower grades of bituminous coal.

A primary object of the invention is to provide a terminal end on the coal feeding tube which may be operated in such a manner that it will not be burned or cracked as frequently happens in the feed tubes heretofore provided. A further primary object of the invention is to provide such a terminal end that may be readily detached and replaced should it become warped or otherwise damaged through the heat of combustion in the burning zone immediately thereabove.

A still further important object of the invention resides in the means for positioning and retaining the feed tube end in a true horizontal position so that the coal may be fed evenly and uniformly distributed therearound within the combustion chamber.

These and other objects and features of the invention will become apparent to those versed in the art in the following description of one particular form of the invention as illustrated by the accompanying drawings, in which Fig. 1 is a top plan view of the stoker construc tion embodying my invention;

Fig. 2, a side elevation;

Fig. 3, a top plan view on an enlarged scale of the burner end of the stoker; and

Fig. 4, a central vertical transverse section on the line 44 in Fig. 3.

Like characters of reference indicate like parts throughout the several views in the drawings.

A feed tube l0, generally tubular in shape, is provided to carry the usual worm H as a means of feeding the fuel through the tube Hi from an upper hopper opening l2, fuel being dumped into this hopper end l2 in any manner as may be desired, the customary manner being by superimposing a hopper (not shown) of suitable dimensions thereabove.

A motor l3, through a suitable gear reduction head H, drives a shaft l5 to cause a worm I6 thereon to turn a worm wheel I! which is fixed on the end of a shaft l8 which extends outwardly from the end of the feed worm II.

On the burner end of the tube [0 are integrally attached a number of brackets l9, Fig. 4. Each of these brackets l9 it attached to the side of the tube ill, at that part thereof which turns upwardly for delivery to the burner. Furthermore each of these brackets I915 provided with a tapered bore socket, to receive the down-turned tapered foot of an arm extending horizontally therefrom to terminate in an outer upturned fork 2|. At the outer ends of these portions 2| on an offset part are adjustably bolted attaching feet 22. Each of these feet 22 is provided with a slot 23, Fig. 3, through which the securing bolt 24 passes so that the foot 22 may be adjusted along a radial line inwardly and outwardly with respect to the upturned end 25 of the tube l0.

A positioning ring 26 is provided in sectional form, here shown as being in four sections, Fig. 3. Each of the sections of the ring 26 carries a downwardly and inwardly turned arm 21 to ex- I tend under the upturned end of the foot 22. The arm 21 is provided with a slot 28 through -which an attaching bolt 29 is passed to screw-threadedly engage the upper end of the foot 22. Thus it is to be seen that by means of the slots 23 and 28, the sections of the ring 25 may be carried in- 20 wardly or outwardly to accommodate the ring circumference to varying diameters of fire boxes in which the burner is to be employed.

Referring to Fig. 3, the sections of the ring 26 are here shown as being carried outwardly to abut 25 the fire brick 30 of a fire box. By reason of the sectional nature of the ring 26, it is to be noted that, Fig. 3, there is a gap between the ends of the sections which is brought about by reason of the fact that the burner is in this case positioned 30 in a fire box larger than the smallest possible box in which the ring would fit were the ring to be brought down to its smaller diameter when the sections would abut end to end. By forcing these ring segments out against the fire bricks, the inner end of the tube It! is thus firmly and rigidly positioned in the fire box so as to maintain the feed tube l0, and particularly its discharge end in the proper position centrally, vertically, and horizontally within the fire box.

On each of the upturned ends of the bracket arms 20, is positioned a roller 3| on which rests a grate carrier spider32. here shown as being formed in two sections and secured together by the bolts 33. Over the upturned discharge end 25 of the feed tube I0 is revolubly fitted a collar 34, here shown as having a flange dropping down over the outer end of the tube end 25 whereby that end 25 serves as a pilot about which the collar 34 may revolve. The spider 32 has an inner annular flange 35 which engages within an annular groove about the collar 34, Fig. 4. The connection between the collar 34 and the spider 32 is such that there may be some relative expansion between the two members.

The collar 34 is provided with an upper annular groove 36 about its outer periphery to receive the inner ends of the individual grates 31, here shown as eight in number, Fig. l. The grates bear on and are carried by the spider 32 by means of depending lugs 38 which straddle the various arms 39 of the spider 32.

The outer periphery of the spider 32 is provided with a series of teeth 40 in the nature of a ratchet wheel. A rocker arm 4| is pivotally mounted by a pin 5| on a bracket 42 which extends from the side of the tube end 25. One end of this arm 4| extends outwardly under the spider 32 and carries a pawl 43, the upper end of which is formed to engage with the teeth 40, Fig. 3, by inward rocking of the upper pawl end. This engagement of the upper end of the pawl with the teeth is maintained by reason of the weighted lower end of the pawl tending to swing to a normally disposed downward position near the vertical, Fig. 4. Thus by reciprocating the arm 4|, the pawl 43 is reciprocated to carry its upper end in one direction over the sloped sides of the teeth 40 without movement of the spider 32 and then to engage the teeth in travelling in the opposite direction so as to shift the spider and thus turn the grates.

This reciprocation of the arm 4| may be produced by any number of ways, one particular way being herein shown as by a connecting rod 44 which engages the end of the arm 4| which is brought around the tube end 25, Fig. 3, and is connected by its other end to a crank member 45, Figs. 1 and 2. This crank member 45 is here shown as a disc or wheel mounted on the outer end of the shaft l5 to be revolved therewith so that on each revolution of the shaft I5, the arm 4| is reciprocated to advance the spider 32 the predetermined distance.

The structure above described is particularly adapted to a burner in which the normal draft is employed and without forced draft so that the ashes need not be fused to clinkers but may drop through the grates in a finely divided form.

It is to be noted that in the form here shown, the grates are horizontally disposed and that the individual grates 3| carry radially disposed slotlike openings therethrough increasing in number toward the outer portions of the grates so as to give greater areas for the disposal of ash therethrough as well as the admittance of air upwardly therethrough.

In operation, the fuel is dropped in through the hopper opening |2 and the Worm or screw conveys the fuel through the tube III to discharge it upwardly through the end 25 and out through the collar 34 to allow the fuel to build up and drop down in a conical manner to spread outwardly over the grates 31, the continuous rotation of the grates in one direction aiding in distributing the fuel outwardly from the central pile. On each intermittent feed of the fuel, the grates are correspondingly revolved, as above indicated. By reason of the fact that the collar 34 is revolubly positioned on the tube end 25, this collar will permit its being replaced should it become damaged when the heat of combustion of the fuel thereabove might warp it or burn it so as to require replacement. Furthermore, this collar will revolve with the grates 31 and the spider 32 by frictional engagement so that by the continuous wiping action through the coal or fuel, it will tend to remain in a cooler state and also prevent undue heating on one side should the fuel bed burn at a higher rate of combustion on the one side than on the other. The collar 34 is further provided with spiral ribs 50 as means to aid in feeding and distributing the fuel. These ribs exert a coal spreading action as the collar turns.

While I have herein shown and described my invention in the one best form as now known to me, it is obvious that structural variations may be employed without departing from the spirit of the invention, and I, therefore, do not desire to be limited to that precise form beyond the limitations as may be imposed by the following claims.

I claim:

1. In a coal burning stoker for heater combustion chambers agedtuhe having an upturned discharge end, brackets secured to the discharge end and having a slotted portion, a segmental ring having downwardly and inwardly oblique slotted arms, and a member for each bracket connecting it with a corresponding arm adjustable thereon to contact the ring with the walls of the chamber to center said end.

2. In a coal burning stoker for heater combustion, chambers having a wall, a feed tube having an upturned discharge end, brackets radially supported from said discharge end, each bracket having a horizontal slotted foot. a ring in segments adjustable against the wall, each segment having a downwardly and inwardly extending slotted arm and an angle-foot for each arm having a member bolted to the arm and a member bolted to the foot of a corresponding bracket.

3. In a coal burning stoker, a feed tube having an upturned discharge end, a collar rotatably positioned on said end as an extension thereof, grate bars having their inner ends supported from said collar, a grate bar carrier having radial arms, means for revolving the carrierpand lugs depending from the grate bars on each side of respective arms whereby said collar may be revolved through said grate bars.

4. In a coal burning stoker, a feed tube having an upturned discharge end, a collar revolubly mounted thereon as an extension thereof, means for feeding fuel through said tube and out through said collar, and means for revolving said collar as said fuel is fed through said collar, grate bars extending substantially horizontally from said collar as an outward continuation thereof, and means for maintaining said bars in fixed horizontal alignment comprising a spider having radial arms supporting an inner flange engaging the collar and an outer flange upon which the grate bars rest, and lugs in pairs covered by the grate bars straddling the arms of the spider and contacting the outer flange.

5. In a coal burning stoker, a feed tube having,

an upturned discharge end, a collar revolubly mounted thereon as an extension thereof, means for feeding fuel through said tube and out through said collar, and means for revolving said collar as said fuel is fed through said collar, grate bars extending substantially horizonally from said collar as an outward continuation thereof, and means for maintaining said bars in fixed horizontal alignment comprising a spider having radial arms supporting an inner flange engaging the collar and an outer flange upon which the grate bars rest, and lugs in pairs covered by the grate bars straddling the arms of the spider and contacting the outer flange, said bars each being fiat and provided with a plurality of radially extending slots therethrough,

the number and total eflective area of the slots increasing toward the outer end of the bar.

6. In a solid fuel burning stoker, a fuel conveying tube, an upturned discharge end on the tube, a detachable collar mounted over said end, a plurality of detachable grate bars radially extending from the collar, and means for frictionally contacting the bars and collar to drive the collar with the travel of the bars, said bars resting by their inner ends within an annular groove about the collar to form in effect a continuation of the collar, the collar being shiftable with the bars, and a segmental ring expansibly extensible upwardly and outwardly from said end for engaging a combustion chamber wall for centering the tube and collar with the wall.

7. In a coal burning stoker, a fuel conveying tube having an upturned end, arms supported by the upturned end, a grate, means for rotatably supporting the grate from the arms, a longitudinally slotted upturned foot on the arm, a positioning ring in a plurality of radially divided sections, a downwardly and inwardly turned longitudinally slotted arm from each section and bolts through a slot of a foot and an arm, bolting them together in pairs.

ARMAND T. RANKIN. 

